1. Field of the Invention
This invention relates to exercisers and particularly to an exerciser of the type wherein the user sits on a seat in a recumbent position and pedals. In the context of this specification, recumbent is defined as meaning a posture that is between lying down and sitting erect as when a user is sitting on a bicycle seat.
2. Prior Art and Information Disclosure Statement
Differences in motivation to exercise tends to separate the exercising public into categories. In one category, the motivation is to develop explosive strength and/or muscle mass and a comparatively minor amount of endurance in order to excel in a sport that requires that kind of physical development. This kind of exercise involves heavy resistance and the ability to control the resistance very accurately in order to increase the resistance to performing the exercise in small accurately controlled increments. Most all of the equipment developed for this type of exercise involves the use of weights to provide resistance. Free weights are an example of equipment used in this type of exercise. However, apparatus have also been disclosed in which weights provide the resistance but the weights are hung on the apparatus and used in such a way that exercise in important ranges of motion can be performed that cannot be performed by free weights. Examples of this type of apparatus are apparatus manufactured by the Spartan Manufacturing Co. in Santa Clara, Calif. The line of equipment from this company includes a self spotting machine in which exercises can be performed such as the bench press, squat, etc. in which the apparatus provides the user with the capability to lock the bar in any vertical location at any point in his exercise.
Another Spartan apparatus is the "LOWER BODY ISOLATOR" in which the user can perform many exercises for the lower body. The apparatus includes a bench and foot operated levers coupled by a cable and pulley system to a variable weight stack. The operator sits on the bench and performs leg presses beginning with his knees close to his chest and moving his feet in an arc to end the stroke with his legs straight out in front of him.
Another large segment of the exercising public has comparatively little interest in developing strength and/or muscle mass. Their motivation is to maintain good health by performing "aerobic" exercises. These exercise involve only moderate resistance with many repetitions. While it is desirable to have the capability to control the resistive force, the control need not be as precise as characterizes the "anaerobic" type of equipment. Popular exercisers for performing this type of exercise that have appeared on the market include steppers, rowing machines, treadmills and stationary bicycles.
Still another important segment of the exercising public are patients and invalids that MUST have exercise in order to recover from dehabilitating illnesses or operations. Normal procedure is to prescribe walking as soon as the patient is able. However the transition from lying flat on one's back to taking the first steps is often a major one, particularly for stroke victims who have lost their sense of balance. In some cases, the sense of balance is lost completely and permanently but this situation does not diminish the patients need to exercise his lower limbs to improve or maintain cardiovascular function.
U.S. Patent to Sweeney et al is for a stepper (or stair climber) having two pedals, each pedal mounted on its own lever assembly. Each lever assembly includes a lever attached to one end of a sprocket chain whose other end is attached to a spring return. The sprocket chain is looped over a sprocket gear, each gear mounted on its own oneway clutch. The pair of clutches are coupled to a single flywheel. The separate spring return for each lever arm provides that the pedals drive the single flywheel independently of one another. One problem with this device is that a practical length of the lever arm severely restricts the range of travel. Another problem is that the motion of the lever is arcurate rather than linear. Another characteristic of the device is that the restoring force depends entirely on the force constant of the spring. This places a limit on the speed with which the pedal can be returned to its starting position. The most desirable situation, therefore, is to have an effective restoring force that is large throughout the entire range of displacement of the pedal in order to have a sufficiently fast return of the pedal. This can only be achieved approximately by the Sweeney invention by having a long spring as shown in the Sweeney patent. This inherently requires that the spring and section of chain required for the return be quite long which adds additional length and bulk to the apparatus. The device is operated by the user standing erect rather than in a recumbent position, contrary to the object of this invention. Resistive force is imposed on the flywheel by a band. The problem with this type construction for applying resistive force is that the band wears, breaks, and has to be replaced.
U.S. Pat. No. 4,900,013 to Rodgers is for a recumbent exerciser including a pair of pedals (travellers), each slidably mounted on one of a pair of parallel tracks respectively. Each endless chain is looped around its a pair of sprocket gears. One of the sprocket gears is coupled to a flywheel through its own oneway clutch at the other end of the tracks. The two sprockets are coupled together providing that, when one pedal is forced in one direction to drive the flywheel, the other pedal is returned to a starting position so that the pedals do not operate independent of one another. Resistance to turning the flywheel is provided by a friction band around the perphery of the flywheel. The Rogers construction shows the flywheel mounted in back of the seated user. This construction thereby requires that the track be mounted at a lower elevation than the seat of the user which restricts the range of motion for exercising the legs.
U.S. Pat. No. 4,875,674 to Dreissigackercker et al is for an energy absorbing means to be used to measure the power applied by a user operating an exerciser such as a rowing machine. The power dissipated during the exercise is measured and used to disengage the braking force when the force exceeds a predetermined value. In one embodiment, the resistive force is provided by the wind resistance developed by a rotating fan. In another embodiment, the resistive force is imposed by a flywheel provided with a friction band wrapped around its periphery.
U.S. Pat. No. 4,943,050, to Smith is for a one leg exerciser including a wheel with a rubber tire, rotatably mounted with the axle horizontal, providing that the user may stand on one floor and stroke the wheel with the other foot. A roller is adjustably forced against the rubber tire to provide variable resistance to turning.
U.S. Pat. No. 4,261,562 to Flavell is for an electromagnetically regulated exerciser showing but not claiming a cable wrapped around a spool coupled through a one way clutch to an electromagnetic resistance means to provide proportioned isokinetic resistance which increases by an amount that the user exceeds a preset value. The cable around a spool shown in the Flavell patent is configured for pulling by hand using an attached stirrup (co. 2) and could not be used in an application where it is required to maintain a constant line of force applied to pulling the cable. As shown in FIG. 1 the line of force varies as the cable wanders along the spool as the spool turns. In order to overcome this problem in adapting his resistance monitor to a "bicycle" type of exerciser, Flavell dispenses with the spool and cable altogether and incorporates a sprocket chain and socket gear to drive his resistance mechanism This approach suffers from the fact that the chain can slip on the sprocket if the resistance to turning is great enough.
Aerobic exercises, such as are performed using equipment of the type described above in the patents to Rogers, Sweeney, Dreissigackercker, are performed to develop and improve the cardiovascular system which includes not only the heart but also arteries and veins that go to all parts of the body. Many repetitions performed with comparatively light resistance provide the benefit of increasing the density of capillaries, enlarging arteries and reducing deposit buildup in the arteries of those limbs, particularly the legs, which perform this type of exercise. With many people, particularly recovering heart patients, their hearts cannot sustain the exertion required to perform repetitious exercise of the legs even though the vascular system in the legs will benefit. Therefore, it would be advantageous to perform exercises with the legs which are low resistance and repetitious but in which the effort required by the heart is minimized.
Exercises performed with the Sweeneey, Smith and Rogers inventions are aerobic exercises that develop the hamstrings and quadriceps. These apparatus do not exercise the gluteous muscles because none of these apparatus permit the user to bring his knees close to his chest. The basic configuration of these devices does not permit a straight line drive of the feet from a position where the knees are close to the chest to a position where the legs are fully extended. From the standpoint of aerobic conditioning, this is an important failing since the gluteous muscles are the largest most powerful muscles in the body and the most beneficial workout would isolate on the use of these muscles.
Another important failing of these devices is that they do not provide for "COASTING OF THE RESISTANCE MECHANISM":. The consequence of this omission is that the resistance wheel slows down during the return stroke so that the velocity of the wheel becomes a complicated function of not only how fast and hard he applies his driving stroke but also the speed of his return stroke.
Another limitation of the devices of the prior art is they do not accomodate for the fact that the force that can be applied by the legs varies with the degree of extension of the leg. The force that can be exerted when the leg is nearly straight is much greater than the force that can be applied when the knees are close to the chest.